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Impact of non-ideal UE hardware on cell-free massive MIMO network with centralized operation

Science China(Information Sciences) 2024年第4期67卷 255-271页

作者： Ning LI Pingzhi FAN Institute of Mobile Communications Southwest Jiaotong University

This paper investigates the impact of non-ideal user equipment(UE) hardware on a cell-free(CF) massive MIMO(mMIMO) network with centralized operation under spatially correlated channels. The minimum mean-squared error(MMSE) estimator can be derived with the help of the generic non-ideal UE hardware model. It is demonstrated that even if the effective signal-to-noise ratio approaches infinity, pilot contamination and imperfect hardware can cause a non-zero estimation error floor. After that, a lower bound is determined for the ergodic uplink capacity of the centralized CF mMIMO network under non-ideal UE hardware. Moreover, the optimal receive combining vector is obtained to maximize the uplink spectral efficiency(SE). The maximum ratio(MR) and regularized zero-forcing(RZF) combining schemes are offered as alternatives in light of the computational complexity of the MMSE receiver. Comparing the RZF to the MMSE scheme under different levels of hardware impairments, our findings indicate that the RZF receiver suffers a negligible loss in total SE. For MR combining, a novel closed-form uplink achievable SE expression is obtained based on the MMSE estimator and the use-and-then-forget bounding technique. This expression gives vital insights into the achievable uplink performance with UE hardware impairments. Besides, for various hardware impairment factors, the impact of pilot sequence length on average sum SE is disclosed for different receive combining schemes. To increase the overall SE of the max-min fairness scheme, a heuristic fractional power control scheme with UE hardware impairments is developed, which can essentially avoid sacrificing the SE of other UEs while maximizing the SE of the unluckiest UE in the whole network. Finally,our theoretical performance analysis and power control algorithm are validated by simulation results, and fundamental design guidelines are provided for selecting hardware satisfying the practical UE requirements.

关键词： cell-free massive MIMO centralized operation spatially correlated channels hardware impairments channel estimation uplink spectral efficiency optimal receive combining pilot length design fractional power control

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An in-situ study of static recrystallization in Mg using high temperature EBSD

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Journal of Magnesium and Alloys 2024年第4期12卷 1419-1430页

作者： Xu Ye Zhe Suo Zhonghao Heng Biao Chen Qiuming Wei Junko Umeda Katsuyoshi Kondoh Jianghua Shen School of Aeronautics Northwestern Polytechnical UniversityXi’anShaanxiChina Shaanxi Key Laboratory of Impact Dynamic and Its Engineering Application Xi’anShaanxiChina School of Mechanical Engineering Qinghai UniversityXiningQinghaiChina School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’anShaanxiChina Department of Mechanical Engineering University of North Carolina at CharlotteCharlotteNCUSA Joining and Welding Research Institute Osaka University11-1 MihogaokaOsakaJapan

It has been a common method to improve the mechanical properties of metals by manipulating their microstructures via static recrystallization,i.e.,through heat treatment.Therefore,the knowledge of recrystallization and grain growth is critical to the success of the technique.In the present work,by using in-situ high temperature EBSD,the mechanisms that control recrystallization and grain growth of an extruded pure Mg were studied.The experimental results revealed that the grains of priority for dynamic recrystallization exhibit fading competitiveness under static recrystallization.It is also found that grain boundary movement or grain growth is likely to show an inverse energy gradient effect,i.e.,low energy grains tend to swallow or grow into high energy grains,and grain boundaries of close to 30°exhibit superior growth advantage to others.Another finding is that{10-12}tensile twin boundaries are sites of hardly observed for recrystallization,and are finally swallowed by adjacent recrystallized grains.The above findings may give comprehensive insights of static recrystallization and grain growth of Mg,and may guide the design of advanced materials processing in microstructural engineering.

关键词： Pure Mg In-situ HT-EBSD Recrystallization Grain growth

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Iodine enrichment in the groundwater in South China and its hydrogeochemical control

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Journal of Environmental Sciences 2024年第8期142卷 226-235页

作者： Fengping Zhou Qianting Xu Yuyun Chen Weihua Zhang Rongliang Qiu Guangdong Provincial Key Laboratory of Environmental Pollution and Remediation Technology Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil RemediationSchool of Environmental Science and EngineeringSun Yat-sen UniversityGuangzhou 510275China Shenzhen Research Institute Sun Yat-sen UniversityShenzhen 518057China Guangdong Provincial Key Laboratory of Agricultural&Rural Pollution Abatement and Environmental Safety School of Natural Resources and EnvironmentSouth China Agricultural UniversityGuangzhou 510642China Guangdong Laboratory for Lingnan Modern Agriculture Guangzhou 510642China

In North China,iodine-rich groundwater has been extensively studied,but few in South China.This study aimed to investigate the characteristics of iodine-rich groundwater in South China and identify potential contamination sources.The results revealed that the average concentration of iodine in groundwater was 890μg/L,with a maximumconcentration of 6350μg/L,exceeding the permitted levels recommended by the World Health Organization(5–300μg/L).Notably,the enrichment of iodide occurred in acidic conditions(pH=6.6)and a relatively low Eh environment(Eh=198.4 mV).Pearson correlation and cluster analyses suggested that the enrichment of iodide could be attributed to the intensified redox process involving Mn(II),iodine(I_(2)),or iodate(IO_(3)^(−))in the soil.The strong affinity between Mn(II)and I_(2)/IO_(3)^(−)facilitated their interaction,resulting in the formation and mobilization of I^(−)from the soil to the groundwater.Leaching experiments further confirmed that reducing substances(such as sodium sulfides,ascorbic acids,and fulvic acids)in the soil with low dissolved oxygen(DO)levels(3.8 mg/L)promoted the oxidation of I^(−)into I_(2)or IO_(3)^(−),leading to its stabilization.This research provides new insights into the characteristics and mechanisms of I^(−)enrichment in groundwater in South China,and emphasizes the significance of the redox reactions involving Mn(II)and I_(2)/IO_(3)^(−),as well as the influence of soil properties in regulating the occurrence and transportation of iodine species within groundwater systems.

关键词： Iodine enrichment Acid environment Groundwater South China Manganese

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Microbes in mass extinction: an accomplice or a savior?

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National Science Review 2024年第1期11卷 12-15页

作者： Genming Luo Deng Liu Hao Yang China University of Geosciences (Wuhan) State Key Laboratory of Geobiology and Environmental Geology

Microbes include various types of organisms that are invisible to the naked eye,e.g. bacteria, archaea and microeukaryotes. Although the precise number remains largely unknown, microbes are recognized as the unseen majority of our biosphere [1]. As a group of organisms classified by body size, microbes cover a considerable spectrum of metabolisms,

关键词： AFTERMATH

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Turbulence Statistics of Thermo-Buoyancy Supercritical Fuel Flow in a Regenerative Cooling Channel

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Journal of Thermal Science 2024年第1期33卷 126-137页

作者： SUN Feng XIE Gongnan School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Department of Thermal Engineering Tsinghua UniversityBeijing 100084China

Active regenerative cooling with supercritical hydrocarbon fuel is considered as the most promising thermal protection method.The existence of buoyancy force would lead to strongly anisotropic flow and thermal transport characteristics.It is closely related to the cooling performance of the engine.To elucidate the mechanisms of turbulent transport,the large eddy simulation(LES) was performed to assess turbulence statistics within different turbulence scales.The results indicated that the buoyancy and inertial force together dominated the change of turbulent structure.Moreover,the spatial thermal buoyancy effect significantly suppressed the vertical velocity fluctuation.This is due to the laminar motion caused by the buoyancy force,thereby weakening the thermal transport.For the statistics of velocity fluctuation,it was found that the buoyancy force and inertial force greatly weaken the vertical and streamwise velocity fluctuation,respectively.For the statistics of thermal transport,the results pointed out that the near-wall heat transport characteristics need to be paid more attention.The thickness of the temperature mixing boundary layer led to the attenuation of vertical heat flux,which inhibited vertical temperature diffusion and predisposed to extreme conditions of heat transfer deterioration.The results can enhance the academic understanding of the heat transfer mechanism of supercritical fluids,and give guidance for further applications of thermal protection.

关键词： active regenerative cooling large eddy simulation(LES) buoyancy force turbulence statistics

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Electrochemically recycling degraded superalloy and valorizing CO_(2)in the aff ordable borate-modified molten electrolyte

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Tungsten 2024年第2期6卷 382-393页

作者： Xiang Chen Yuan Sun Long Wang Xin Qu Yan Zhao Hong-Wei Xie Di-Hua Wang Hua-Yi Yin Key Laboratory for Ecological Metallurgy of Multimetallic Mineral of Ministry of Education School of MetallurgyNortheastern UniversityShenyang 110819China Institute of Metal Research Chinese Academy of ScienceShenyang 110016China School of Resource and Environmental Science Wuhan UniversityWuhan 430072China

Integrating electrochemical reduction of CO_(2)and electrochemical oxidation to recycle degraded superalloys is a promising solution to ease resource scarcity and safeguard environmental sustainability.Herein,we propose an electrochemical technique for the conversion of bulk superalloy scraps and CO_(2)into oxide powder at the anode and solid carbon at the cathode,respectively.In particular,a borax-modifi ed CaCl_(2)-based molten salt electrolyte is used for enhancing the electrochemical oxidation of superalloy scraps.At a temperature of 700℃and a voltage of 2.8 V,90.55 wt.%of alloy scraps were oxidized in a molten CaCl_(2)–NaCl–CaCO_(3)–Na_(2)B_(4)O_(7)with an acid–base ratio(K_(a/b))of 1.The synergy of Cl−and B_(4)O_(7)2−of electrolyte prevents the passivation of the alloy anode and enables continuous oxidation.Furthermore,the Ni and Co in the anode products are recovered by sulfation roasting with recovery efficiencies of 85.58%and 95.27%for Ni and Co,respectively.Overall,modulating the alkalinity of the electrolyte for enhancing oxidation/pulverization of alloy scrap anode provides new insight into electrochemically recovering superalloy scraps.

关键词： Superalloy scraps Recycling Molten salt Alkalinity Electrochemical oxidation Cobalt

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Supramolecular complex glycoconjugate vaccine generates self-enhancement effects for carbohydrate antigen delivery

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Chinese Chemical Letters 2024年第2期35卷 317-322页

作者： Han Lin Yanchun Li Kun Zhou Dan Li Hangyan Yu Jie Zhao Haofei Hong Zhifang Zhou Zhimeng Wu Key Laboratory of Carbohydrate Chemistry & Biotechnology Ministry of EducationSchool of BiotechnologyJiangnan UniversityWuxi 214122China

Targeting delivery of tumor-associated carbohydrate antigen(TACA)-based vaccine to antigen-presenting cells(APCs)mediated by endogenous antibodies can improve the immunogenicity of TACA.However,an essential requirement of this approach is to generate high titers of endogenous antibodies in vivo through pre-immunization,which complicates the immunization procedure and may cause side effects.Herein,we report a new generation of APC-targeting TACA-based supramolecular complex vaccine,assembled by sialyl Thomsen-nouveau-bovine serum albumin-adamantine(sTn-BSA-Ada)and heptavalent rhamnose(Rha)-modifiedβ-cyclodextrin(β-CD)via host-guest interaction.The complex vaccine retained anti-Rha antibodies recruiting capability and facilitated the APCs uptake of the vaccine via the interaction of the Fc-domain with the Fc receptors on APCs.We demonstrate that direct immunization of complex vaccine elicited anti-Rha and anti-sTn specific immune response synchronously,generating a novel self-enhancement effect that can improve the antigen delivery to APCs in high efficacy.The structure-activity relationship(SAR)study proved that complex vaccine 4 with polyethylene glycol 6(PEG 6)linker in host molecule provoked a robust and specific sTn immune response comparable to the pre-immunization approach.The antisera induced by complex vaccine,either through direct immunization or pre-immunization,exhibited equal potency of cytotoxicity against the sTn expression cancer cells.This study provides a general platform for TACA-based vaccines with self-enhancement effects without the need for pre-immunization.

关键词： Glycoconjugate vaccine Endogenous antibody APC-targeting Supramolecular complex sTn antigen

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Pathological BBB Crossing Melanin-Like Nanoparticles as Metal-Ion Chelators and Neuroinflammation Regulators against Alzheimer’s Disease

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Research 2024年第1期6卷 687-706页

作者： Qianqian Huang Chaoqing Jiang Xue Xia Yufan Wang Chenxing Yan Xiaorong Wang Ting Lei Xiaotong Yang Wenqin Yang Guo Cheng Huile Gao Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry West China School of PharmacySichuan UniversityChengdu 610041P.R.China Laboratory of Molecular Translational Medicine Center for Translational MedicineKey Laboratory of Birth Defects and Related Diseases of Women and Children(Sichuan University)Ministry of EducationDepartment of PediatricsWest China Second University HospitalSichuan UniversityChengdu 610041P.R.China

Inflammatory responses,manifested in excessive oxidative stress and microglia overactivation,together with metal ion-triggered amyloid-beta(Aβ)deposition,are critical hallmarks of Alzheimer’s disease(AD).The intricate pathogenesis causes severe impairment of neurons,which,in turn,exacerbates Aβaggregation and facilitates AD progression.Herein,multifunctional melanin-like metal ion chelators and neuroinflammation regulators(named PDA@K)were constructed for targeted treatment of AD.In this platform,intrinsically bioactive material polydopamine nanoparticles(PDA)with potent metal ion chelating and ROS scavenging effects were decorated with the KLVFF peptide,endowing the system with the capacity of enhanced pathological blood–brain barrier(BBB)crossing and lesion site accumulation via Aβhitchhiking.In vitro and in vivo experiment revealed that PDA@K had high affinity toward Aβand were able to hitch a ride on Aβto achieve increased pathological BBB crossing.The engineered PDA@K effectively mitigated Aβaggregate and alleviated neuroinflammation.

关键词： oxidative aggregation chelating

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Mapping out the reaction network of humin formation at the initial stage of fructose dehydration in water

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Green Energy & Environment 2024年第6期9卷 1016-1026页

作者： Xing Fu Yexin Hu Ping Hu Hui Li Shuguang Xu Liangfang Zhu Changwei Hu Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengduSichuan610064China State Key Laboratory of Southwestern Chinese Medicine Resources Innovative Institute of Chinese Medicine and PharmacyChengdu University of Traditional Chinese MedicineChengduSichuan611137China

The formation of humins hampers the large-scale production of 5-hydroxymethylfurfural(HMF)in biorefinery.Here,a detailed reaction network of humin formation at the initial stage of fructose-to-HMF dehydration in water is delineated by combined experimental,spectroscopic,and theoretical studies.Three bimolecular reaction pathways to build up soluble humins are demonstrated.That is,the intermolecular etherification of β-furanose at room temperature initiates the C12 path,whereas the C-C cleavage of a-furanose at 130-150℃ leads to C11 path,and that of open-chain fructose at 180℃ to C11' path.The successive intramolecular dehydrations and condensations of the as-formed bimolecular intermediates lead to three types of soluble humins.We show that the C12 path could be restrained by using HCl or AlCl_(3) catalyst,and both the C12 and C110 paths could be effectively inhibited by adding THF as a co-solvent or accelerating heating rate via microwave heating.

关键词： Carbohydrates 5-hydroxymethylfurfural Reaction network Soluble humins Tautomer

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Enhanced electrochemical performance of Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3) solid electrolyte by anion doping

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Nano Research 2024年第3期17卷 1465-1472页

作者： Jingrui Kang Xu Guo Rui Gu Honglei Hao Yi Tang Jiahui Wang Li Jin Hongfei Li Xiaoyong Wei Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education&International Center for Dielectric ResearchSchool of Electronic and Information EngineeringXi’an Jiaotong UniversityXi’an 710049China School of Energy and Materials Shanghai Key Laboratory of Engineering Materials Application and EvaluationShanghai Polytechnic UniversityShanghai 201209China

Nowadays,the majority of the studies on the substitution are focused on cations(such as Y^(3+),Ti^(4+),P^(5+),etc.)in Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP),while there are few studies on the substitution of anion O^(2-).In this work,the modified LATP with a series of LiCl(LATPClx,x=0.1,0.2,0.3,0.4)additives is prepared to enhance ionic conductivity.The successful introduction of Cl-makes the length of the c axis decrease from 20.822(2)to 20.792(1)Å,and the bulk conductivity of 2.13×10^(-3) S·cm^(-1) is achieved in LATPCl_(0.3).Moreover,the Al/Ti-O1/Cl1 and Al/Ti-O_(2)/Cl_(2) distance decrease,while the Li1-O_(2)/Cl_(2) distance increases.Lithium ions migrate more easily in the nanochannel of M3-M1-M3.In addition,the LiCl additive increases the relative density and the grain boundary conductivity of LATPClx compounds.Naturally,a higher ionic conductivity of 2.12×10^(–4) S·cm^(-1) and a low activation energy of 0.30 eV are obtained in LATPCl_(0.3).Correspondingly,the symmetric cell exhibits a low overpotential of±50 mV for over 200 h in LATPCl_(0.3).The solid-state Li|LATPCl_(0.3)|NCM811(NCM811=LiNi0.8Co0.1Mn0.1O_(2))battery exhibits high initial capacity 185.1 mAh·g^(-1) with a capacity retention rate of 95.4%after 100 cycles at 0.5 C.This result suggests that LiCl additive is an effective strategy to promote electrochemical properties of LATP solid electrolyte and can be considered for reference to other inorganic solid electrolytes systems.

关键词： Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)solid electrolyte anion doping ionic conductivity cyclic performance

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